This invention relates to a portable placer exploration and sampling apparatus designed for rapid and low-cost evaluation of valuable mineral content of alluvial, eluvial residual placers. Historically, placers have been one of the most important sources of precious minerals and gems such as gold, diamonds, platinum, emeralds, rubies and sapphires. Valuable minerals are not distributed uniformly through the typical placer deposit. Heavy minerals, in general, and gold, in particular, typically are confined to narrow, discontinuous pay streaks with little or no value between them and typically are concentrated at bedrock levels beneath a great amount of relatively barren overburden. Therefore, representative samples, although critical to exploration, selection and future development of placers are difficult to obtain.
Typically, land-based placer sampling methods have evolved into two categories—a large number of small samples or a lesser number of bulk samples. Small samples typically have been taken with gasoline powered churn drill, 6″ drive pipe casing and sample baler. Bulk samples typically are taken by several methods, including hand dug excavation, machine-dug shafts, backhoe pits or trenches and bulldozer trenches.
With the exception of hand excavation, all of the above sampling methods are expensive and difficult, if not impossible, to transport into inaccessible areas. As a result, most placer development has occurred in the relatively accessible placer deposits of the world. One of the primary limitations on opening up virgin placer areas has, therefore, been the high cost of evaluating the economic risk and feasibility of further development of relatively inaccessible sites. This invention addresses this limitation by providing features which have not previously been available in traditional placer sampling methods, including                light weight and ease of assembly of components permits sampling of placers considered inaccessible to traditional sampling methods,        low capital and operating costs and simplicity of operation allows application of a large number of systems and employment of a large number of unskilled workers for wide scale testing of candidate placers,        large sample volumes provide for increased sampling accuracy and, in many cases, financing of the sampling program through recovered precious mineral values,        rapidly samples to bedrock without sloughing or handling of overburden,        cleans and recovers materials trapped in bedrock cracks and fissures,        enables sampling of mineral values from up to one and a half cubic foot per foot of depth to bedrock,        maximizes sampled volume with minimum processing, i.e. only about 2% of sampled volume need be processed,        reduces sampling costs to a fraction of traditional methods, and        minimizes environmental damage.To my knowledge, no prior art has been capable of providing all of the above functions, as a self-contained, integral unit, capable of being disassembled and transported into inaccessible areas. The references cited are described as large units adapted primarily for water-based operation from barges with land-based operation as an afterthought. Since most of the placers of the world are in areas inaccessible to motorized equipment, portability by means of manpower, pack animal, small boat or helicopter must be a prime consideration.        